2025 MME Rally left me stranded... HVBJB failed...

[Mach-Lee]

Interesting.

I'm sure that there are those at Ford on the Mach-E team that could give a very good reason for accessory mode NOT enabling the DC/DC converter. But I wish, naively perhaps, that it did.

For lots of reasons and scenarios.

Because of the legacy module setup. On ICE vehicles KOEO drains the 12V battery since the alternator can't run. Same on the Mach-E. The car has to be fully started "READY" to enable the high voltage systems to charge the 12V battery.

IMO they should just eliminate accessory mode so it doesn't even work unless you press the brake pedal with the start button. But that would complicate module programming which requires KOEO state to exist. So because of module programming needs, it's the way it is.

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[Snakebitten]

Because of the legacy module setup. On ICE vehicles KOEO drains the 12V battery since the alternator can't run. Same on the Mach-E. The car has to be fully started "READY" to enable the high voltage systems to charge the 12V battery.

IMO they should just eliminate accessory mode so it doesn't even work unless you press the brake pedal with the start button. But that would complicate module programming which requires KOEO state to exist. So because of module programming needs, it's the way it is.

But that's actually an argument for taking advantage of the EV architecture and having accessory mode being a mode that taps the stored energy with the DC/DC converter.

On the Powerboost F150, its leveraged by some as a "2-step startup" procedure. (I use the procedure consistently)
It was discovered as a work around for the "Stop Safely Now" error message that some of the 2023 model Powerboost were experiencing shortly after being released. Turned out that if you did Step 1, (accessory mode) and allowed all the modules a few seconds to boot up and handshake, BEFORE the command to start the ICE or put the truck in Ready mode, the Stop Safely Now error was avoided. Of course it turned out to be some unintended software glitch from something Ford changed at production time, and a software update eventually solved the issue. But that was after a fair number of brand new truck owners were making their first payment on a vehicle they couldn't drive. It was ugly.

The small percentage of owners that were members of the forum were fortunate enough to be aware of the work around. The DC/DC converter being available in accessory mode is a good thing, in my opinion. Afterall, Ford themselves are currently rolling out a solution to a Mach-E problem by enabling the DC/DC converter to be functional in a circumstance it previously wasn't. ?

 

[heisnuts]

I would be very surprised if it is the battery causing the problem here. OP says he drove for a while before getting the SVS. That would tell me the 12V had a long time to charge due to the OPs road trip they were on.

 

[E90alex]

Because of the legacy module setup. On ICE vehicles KOEO drains the 12V battery since the alternator can't run. Same on the Mach-E. The car has to be fully started "READY" to enable the high voltage systems to charge the 12V battery.

IMO they should just eliminate accessory mode so it doesn't even work unless you press the brake pedal with the start button. But that would complicate module programming which requires KOEO state to exist. So because of module programming needs, it's the way it is.

It seems they have some ability to override or change the legacy ICE programming since with the new recall they are changing it to keep the DC-DC active for 12 minutes after key off.

Really for an EV they should just program it to keep the DC-DC on and active from the moment of unlocking or opening a door until X minutes after doors are closed/locked (or 12 minutes after key off like the recall fix).

 

[JavaBob]

Sorry about your luck, but is that Velocity blue?
I'm ordering that same color combo (with black wheels) so nice to see one IRL even if it's on a towtruck

I have a Velocity Blue Metallic on order. My dealer had one coming in with the glass roof, which I di

Sorry about your luck, but is that Velocity blue?
I'm ordering that same color combo (with black wheels) so nice to see one IRL even if it's on a towtruck

Well, I don't know what happened there. Anyway, the dealer one came in with the glass roof cracked. Hopefully I can attach a pic. Needless to say I didn't take it and went ahead and ordered one. MSRP went up $2K but I won't have to pay for the $1,600 roof so almost a wash. Hopefully I'll get a build date this year!

 

[XPLOR]

I have a Velocity Blue Metallic on order. My dealer had one coming in with the glass roof, which I di

Well, I don't know what happened there. Anyway, the dealer one came in with the glass roof cracked. Hopefully I can attach a pic. Needless to say I didn't take it and went ahead and ordered one. MSRP went up $2K but I won't have to pay for the $1,600 roof so almost a wash. Hopefully I'll get a build date this year

Hope everything goes well for you on your order! It is a nice color!

 

[JavaBob]

I agree. I almost went with the red because there's one on a lot locally but it's way too pink IRL. I was originally concerned about the blue because my wife had a Velocity Blue Bronco but the metallic puts in a whole other class.

 

[ChasingCoral]

There was previous discussion of moving to a 48V LVB system, I think the dumpsterTruck was doing this? Would this help with this particular issue, or would it just complicate the issue?

Note that Tesla just updated both the M3 and the MY and didn’t put 48v on those either.

 

[ChasingCoral]

12V vs 48V in and of itself wouldn’t make a difference. But a 48V battery would most likely be a proprietary Li-ion.

The issue is relying on a lead acid battery. A Lithium-ion LV battery would be designed to last the life of the car like the HV battery would and would basically eliminate all 12V issues, but there’s no standardized/commoditized off the shelf 12V Li-ion battery and it would be much more expensive than lead acid.

Tesla has switched to proprietary Li-ion LV batteries since like 2022 and is the only EV company that has done so I believe. Some high end German cars use a Li-ion 12V for weight savings but they’re like $1500+.

You’d have to use a heated Lithium battery to work in cold weather.

 

[E90alex]

You’d have to use a heated Lithium battery to work in cold weather.

Not sure if Teslas lithium LV are heated or not. But lithium batteries can discharge ok in the cold, especially for something relatively low demand like flipping the HV contactors. It’s just not good to charge them when cold.

 

[ChasingCoral]

Not sure if Teslas lithium LV are heated or not. But lithium batteries can discharge ok in the cold, especially for something relatively low demand like flipping the HV contactors. It’s just not good to charge them when cold.

We have enough trouble with those tiny batteries already. Not being able to charge them in the cold while running would be a real issue in cold climates during the winter. You would either need a heated battery or a battery heater. The car would also need a 12v battery temperature monitoring system and a LVB controller that limits charging to times when the battery core is above freezing. Remember, there's not much up there to heat the battery.

 

[E90alex]

We have enough trouble with those tiny batteries already. Not being able to charge them in the cold while running would be a real issue in cold climates during the winter. You would either need a heated battery or a battery heater. The car would also need a 12v battery temperature monitoring system and a LVB controller that limits charging to times when the battery core is above freezing. Remember, there's not much up there to heat the battery.

Yes it would require different equipment and different design/engineering considerations different charging strategies, all of which increase cost. Which is why no one else has really gone to a lithium LV battery.

But lithium batteries can be far more deeply discharged than lead acid so you don’t have to charge them as often. They also can charge much faster than lead acid.

They can also be designed/placed in such a way where they can be passively or actively heated and cooled if needed. We’re not talking just dropping in a lithium battery where the lead acid is and doing nothing else. (Which is why drop in lithium batteries peddled by some companies like ohmmu do not have great reliability).

Again, Tesla has already been doing this since 2022 in all climates and with far less issues than lead acid batteries.

 

[dalola]

Because of the legacy module setup. On ICE vehicles KOEO drains the 12V battery since the alternator can't run. Same on the Mach-E. The car has to be fully started "READY" to enable the high voltage systems to charge the 12V battery.

IMO they should just eliminate accessory mode so it doesn't even work unless you press the brake pedal with the start button. But that would complicate module programming which requires KOEO state to exist. So because of module programming needs, it's the way it is.

Agree, acc mode on an EV is retarded. Ford should be able to figure out proper module programming for ICE vs EV modules, even if they are common parts. I think, eventually, we will see this happen. It will cure a lot of recall/warranty issues, and most likely, improve the OEM's bottom line/customer satisfaction. Most OEM's are still behind in software vs hardware development, especially in EV's.

 

[RickMachE]

I have a Velocity Blue Metallic on order. My dealer had one coming in with the glass roof, which I di

Well, I don't know what happened there. Anyway, the dealer one came in with the glass roof cracked. Hopefully I can attach a pic. Needless to say I didn't take it and went ahead and ordered one. MSRP went up $2K but I won't have to pay for the $1,600 roof so almost a wash. Hopefully I'll get a build date this year!

I'm confused. You were buying a vehicle that arrived at the dealership with a cracked roof. They replace it prior to delivery, costs you nothing. What am I missing?

 

[JavaBob]

First off, I didn't want the glass roof, it was just built that way. I decided I could live with it, though, so I put a deposit down on it. We were literally on the way to pick it up when the salesperson called and told me about the roof. He made no attempt to try to get me to take it and have the roof replaced later. He said they were working with Ford to figure out what to do with it. Past experience has told me that replacing windshields is problematic in turns of leaking so, by extension, replacing an entire glass roof could be a significant problem. Since I don't need the MME and I'm keeping my ICE vehicle I decided to just order one to get what I want. It's been about 3 months now and the vehicle is still sitting in their lot with the cracked roof.

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